1. Field of the Invention
The present invention relates to reduced odor or odor-free esters, and more particularly to odor-free C12-C15 alkyl benzoate esters, octanoate esters, glycol dibenzoate esters, and other emollient esters, their process of manufacture and their use in cosmetics and personal care products as carriers or vehicles, or a diluents, solvents, plasticizers, emollients and solubilizers.
2. Description of the Related Art
Esters are known for a variety of different applications for cosmetic, pharmaceutical and medicinal purposes.
Numerous references describe the production and use of benzoic acid esters. None of these references teach or suggest the specific novel reduced odor or odorless benozate esters of this invention or the use of these and other reduced odor benzoate esters in cosmetics and personal care products.
For example, benzoate esters of certain alcohols and alcohol mixtures and their uses are disclosed in assignee""s U.S. Pat. Nos. 4,323,694; 4,322,545; and 4,275,222, all to Scala; and U.S. Pat. Nos. 4,791,097; 5,270,461; and 5,271,930, all to Walele et al. The disclosures of these patents are incorporated herein by reference.
U.S. Pat. Nos. 4,323,694; 4,322,545; and 4,275,222 to Scala disclose benzoic acid esters and processes for making same, using methane sulfonic acid as a catalyst at temperatures of about 160xc2x0 C. to 175xc2x0 C. The catalyst containing crude ester is washed and dried. Although there is no specific teaching of such washings in Scala, the industry practice is to neutralize any residual acidity with an alkali water wash. The ester is then further washed, as necessary, and dried. The Scala patents do not disclose using stannous oxalate as a catalyst, running the reaction at very high temperatures (220xc2x0 C. or more), or removal of the catalyst as a process improvement to improve the odor of the resultant esters.
U.S. Pat. Nos. 4,791,097; 5,270,461; and 5,271,930 to Walele et al. disclose benzoic acid esters and processes for making same. The processes disclose reacting benzoic acid with an alcohol, using a catalyst, heating and then cooling, and collecting distillate. The mixture was subsequently treated with, among other things, hydrogen peroxide, and heated at 80xc2x0 C.-100xc2x0 C. The ester component was collected, washed with neutralization, and then refined by washing and drying.
U.S. Pat. No. 2,997,494 to Brown discloses a method of preparing vinyl esters of carboxylic acids.
U.S. Pat. No. 3,843,719 to Brady discloses a process for preparing esters of carboxylic acids.
U.S. Pat. No. 4,304,925 to Watanabe et al. discloses a process for obtaining esters by reacting an organic carboxylic acid or its anhydride with an alcohol in the presence of an organometallic compound as a catalyst. There is no recognition of steps taken specifically to improve the odor of the esters.
U.S. Pat. No. 4,506,091 to Deardorff discloses a method for refining esters without the necessity of washing procedures. Improvement of the odor of the ester is not contemplated or recognized.
U.S. Pat. No. 5,302,746 to Koono et al. discloses a process for producing a carboxylic acid ester, using a countercurrently contacting column for neutralization.
U.S. Pat. No. 5,693,316 to Pereira et al. discloses fatty alkoxylate esters of aliphatic and aromatic dicarboxylic acids.
U.S. Pat. No. 5,783,173 to Bonda et al. discloses a sun-screen composition containing a UV-B dibenzoyl-methane derivative such as PARSOL 1789, and a stabilizer/solubilizer for the dibenzoylmethane derivative, and mixtures thereof.
However, among the foregoing patents, none have the unique properties of the ester compositions described and claimed herein. None disclose or suggest a process for the production of esters and emollient esters which are odorless or which have extremely low odor due to the absence of odor-causing species such as aldehydes, carbonyl compounds, and the like. This is a vital property in numerous applications, as the esters may be incorporated into personal care products, where absence of odor is critical to consumer acceptance.
This is due in part to the failure of prior processes to recognize that removal of the catalyst improves the odor, and to the use of certain unsuitable catalysts. For instance, the Scala patents referred to above use Methane Sulfonic Acid (MSA) as a catalyst. The problem with using MSA as a catalyst is that it is soluble in the organic reactants. MSA dissolves in the organic matter during reaction and cannot be physically removed by filtration from the reaction mix. It is not heterogeneous as is the case with stannous oxalate and metal oxides. However, it is neutralized in the neutralization/washings which follow subsequent to the esterification reaction. So even after neutralization and washing, odorous esters are formed because the intrinsic odor from the raw materials remains. Another problem with MSA is that the reaction cannot be run at high temperatures; exceeding temperatures of about 170xc2x0 C. to 175xc2x0 C. results in formation of chocolate-colored organic matter. It has been found by applicants that the darker the ester product, generally the worse the odor. Esters made using MSA as a catalyst have been found by applicants to be odorous.
In developing formulations for personal care products, it is critical to utilize a product that lacks odor. Many emollients have a characteristic obnoxious odor that is difficult to mask. Masking odors is an inordinately difficult and expensive task. Known methods of producing esters and ester-emollients result in esters which are odorous, i.e., they have an MFL, a minimum fragrance level. This is a disadvantage because perfumes must then be added to mask or overcome the MFL. Additionally and/or alternatively, the esters are deodorized by various methods including filtering, bleaching clays, or steam distilling the esters. Masking the obnoxious odors of many emollients is both difficult and expensive.
The disadvantages of the known methods of producing esters and emollient esters are overcome by the process of the present invention. Unexpectedly, the esters of the invention are odorless or have a very small MFL, avoiding the need for perfumes and deodorization.
It is an object of the present invention to provide a process or producing esters and emollient esters which have a low odor, or MFL, or which are odorless, due to the absence of odor causing species such as aldehydes, carbonyl compounds, and the like.
It is another object of the invention to provide a process for making reduced odor or odorless esters and emollient esters for use in cosmetics and personal care products.
It is yet another object of the invention to provide a process for making reduced odor or odorless esters and emollient esters for use in products where the addition of perfumes is objectionable.
It is a further object of the invention to provide a process for making esters and emollient-esters for use in cosmetics and personal care products which reduces the need for perfumes in cosmetics and personal care products.
Yet another object of the invention is to provide a method for producing esters and emollient esters which obviate the need for extraneous filtration or deodorizing techniques to remove odor.
Another object of the invention is to provide a method of producing reduced odor or odorless cosmetics or personal care products using certain specific benzoic acid esters.
It is another object of the invention to provide low-odor or non-odorous esters and emollient esters by reducing or substantially eliminating odor causing species.
Yet another object of the invention is to provide novel esters which may serve as emollient""s and which may also modify the odor characteristics of the products in which they are used.
It is another object of the invention to provide reduced odor or non-odorous esters and ester emollients for use in products where the use of perfumes is objectionable.
It is another object of the invention to provide reduced odor or non-odorous esters and ester emollients for use in cosmetics and personal care products to reduce the use of perfumes in these products.
Yet another object of the invention is to provide esters and ester emollients for use in products where the odor of the ester may interfere with that of other ingredients.
These and other objects are accomplished by providing an improved process for preparing reduced-odor or odorless esters, preferably benzoate esters, octanoate esters, aliphatic emollient esters and glycol dibenzoate esters. The improved process comprises, in part, removing the esterification catalyst from the crude ester after the esterification reaction is substantially complete, before neutralization of acidity. The resultant ester compositions are odorless or have substantially reduced odor as compared to commercially available esters.
The novel esters of this invention have unique properties in that they have reduced odor or are substantially odor-free. This property makes the compositions useful as a vehicle or carrier, emollient or solubilizer for toiletry and cosmetic formulations and personal care products, such as hair creams, hand cleaners, bath oils, suntan oils, anti-perspirants, perfumes, colognes, cold creams, electric pre-shaves, eye and throat oils, finger nail polish, topical pharmaceutical ointments, lipsticks, stick rouge, skin lotions and creams, skin moisturizers, cleansing creams, and after-bath splash and lotions, as well as other formulations. The foregoing list is only exemplary of the type of compositions in which the esters of this invention may be used, and, as such, is not to be considered limiting.
The odor-free emollient esters produced by the process of the invention include:
a. Benzoate Esters in general, and C12-15 Alkyl Benzoate Esters in particular, as set forth in Example Nos. 1 through 11 below;
b. Octanoate Esters, and in particular, aliphatic cetearyl octanoate esters, as set forth in Example Nos. 12, 13, and 27 below.
c. Aliphatic.emollient esters, specifically, C12-15 Alkyl Octanoate Esters, as set forth in Example Nos. 14, 15, 25 and 26, below;
d. Glycol Dibenzoate esters, specifically Dipropylene Glycol Dibenzoate, as set forth in Example Nos. 16 and 17, below.
The preferred alcohol precursors used in preparing the odor-free benzoic acid esters of the invention are selected from the group consisting of alcohols containing from 3 to 22 carbon atoms, and preferably C12-C15 alcohols. Typical examples include octyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, behenyl alcohol, oleyl alcohol, isostearyl alcohol, arachidyl alcohol, etc. The preferred alcohol is Neodol 25 (Shell Chemical Company).
The odor-free octanoate esters of the invention are obtained by reacting ethylhexanoic acid with an alcohol in accordance with the process of the invention. The alcohol is selected from the group consisting of alcohols containing from 3 to 22 carbon atoms, and preferably C12-C15 alcohols. Typical examples include octyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, behenyl alcohol, oleyl alcohol, isostearyl alcohol, arachidyl alcohol, etc. The preferred alcohol is Neodol 25 from Shell Chemical Company.
The odorless aliphatic emollient esters of the invention are made by reaction of alcohols and carboxylic acids in accordance with the process of the invention. The alcohols may be alcohols such as those comprising 3 to 22 carbon atoms, e.g., octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, arachidyl alcohol, behenyl alcohol, isostearyl alcohol, etc. Preferably, the alcohol is a C12-C15 alcohol. Most preferably, the alcohol is Neodol 25 from Shell Chemical Co. The carboxylic acids may be selected from the group of carboxylic acids consisting of linear or branched, with 4 to 22 carbon atoms, such as octanoic acid, decanoic acid, ethylhexanoic acid, lauric acid, myristicacid, palmitic acid, stearic acid, oleic acid, behenic acid, isostearic acid and arachidic acid.
The odor-free glycol dibenzoate esters of the invention are prepared by reacting a glycol with benzoic acid in accordance with the process of the invention. The glycol comprises from 3 to 12 carbon atoms, preferably 6 to 12 carbon atoms. Most preferably, the glycol is dipropylene glycol.
The foregoing list is only exemplary of the type of precursors on which the emollient esters may be based, and, as such, is not to be considered limiting.
In a specific embodiment, and by way of illustration, this invention contemplates the production of low odor or odorless emollient-esters in accordance with the following equation:
A. Octanoate Ester Chemistry
FINESTER CST-8, also known as cetearyl octanoate, is a branched chain emollient ester; FINESTER EH-25 is an octanoate ester of C12-15 alcohol.
In the following discussion, FINESTER CST-8, FINESTER EH-35, FINSOLV PG-22, and FINSOLV TN are registered trademarks of Finetex, Inc., Elmwood Park, N.J., 07407.
Reacting 2-Ethyl Hexanoic Acid+C16-18 Alcohol (may be Cetyl or Stearyl Alcohol) in the presence of a catalyst produces Cetyl/Stearyl/Ethyl Hexanoate (also known as Cetyl/Stearyl Octanoate). 
Where R=C16-C18 Alkyl (sold as FINESTER CST-8)
Reacting 2-Ethyl Hexanoic Acid+C12-15 Alkyl Alcohol in the presence of a catalyst produces C12-15 Alkyl Ethyl Hexanoate (also known as C12-15 Alkyl Octanoate), as follows: 
Where R=C12-15 Alkyl (Sold as FINESTER EH-25)
The odor-free, emollient benzoate esters of this invention are produced by reacting benzoic acid with an alcohol, as is known in the art, and as taught in the Scala and Walele et al. patents, supra. A catalyst is present during the reaction. The process for preparing the esters is preferably a batch process, but may also be a continuous process, for instance, conducted in a continuous extractor.
Superior, reduced odor or odorless esters are produced in part by removing the catalyst from the mass after the reaction is complete and before neutralization. The catalyst is preferably removed by filtration so that the crude ester mass is free of the catalyst particulate matter. Thereafter, the crude ester is worked up by neutralizing, washing and drying. The resultant processed refined ester is odorless or practically odorless as compared to prior art esters.
Applicants have discovered that removal of the catalyst from the mass after the reaction is complete and before neutralization has multiple benefits. These include reducing the use of alkalis for neutralization of organic acidity, thus reducing the formation of oxalic acid neutral species. Another benefit is reducing loss during the washing procedure by way of reducing the amount of inseparable emulsion phase (interphase) which causes loss of product, thus improving the yield. Removing the catalyst before neutralizing and washing the crude ester improves the yield and odor of the resultant ester and results in a sharp separation during the washing.
Thus, applicants have found that removal of the catalyst advantageously prevents the occurrence of undesirable side reactions which may interfere with formation of the desired esters. In the case of stannous oxalate as the catalyst, these undesirable side reactions include effects of alkalis on alcohol or ester, in the presence of stannous oxalate; the reaction of stannous oxalate with hydrogen peroxide to form oxalic acid; and oxidation of unreacted alcohol to aldehyde and ketone in the presence of hydrogen peroxide and stannous oxalate.
Another factor in reducing odor is the use of sodium borohydride for the treatment of the alcohol., i.e., C12-15 alcohol, before reacting with Benzoic Acid and before contacting the mixture of reactants and catalyst, to convert aldehyde and other species in the reaction to alcohol. Use levels of sodium borohydride can be from 10 ppm to 500 ppm.
Other starting alcohols or glycols (besides C12-15 alcohols), such as dipropylene glycol or C16-C18 alcohol, may be pretreated with sodium borohydride, but it is not a requirement of the process of the invention to do so. As shown in Example No. 1 below, Neodol 25 (Shell Chemical Company) is not pretreated with Sodium Borohydride, yet good odor results were obtained even without pretreatment. This is thought to be due to the fact that in this Example where the catalyst was removed, and hydrogen peroxide was not used in any step during the reaction and washing, there is such a minute amount of impurities in the form of aldehydes and ketones that, even without using sodium borohydride, the odor is very good. While the color of the ester is slightly higher, it is still good (less than 20 APHA).
In contrast, as can be seen from Example #2 below, when the starting alcohol was not pretreated with sodium borohydride, and the catalyst was not removed, and hydrogen peroxide was added to the crude ester before the washing step, the resulting ester had a mild to strong odor, there was a loss of yield in the form of increased interphase, but the resulting ester had very good color.
As demonstrated in Example #4 below, where the alcohol is pretreated with sodium borohydride, the catalyst is removed from the reaction mass, and hydrogen peroxide is added before neutralization of acidity, the resulting ester has a mild odor, there is loss of some yield, and the ester has a good color.
In summary, esters with the best odor and yield are obtained is where there is no pre-treatment with sodium borohydride, the catalyst is removed, and hydrogen peroxide is not added, as demonstrated in Example #1. Esters having adequate, but not as good, odor and yield, are obtained where there is no pre-treatment with sodium borohydride, the catalyst is removed, and hydrogen peroxide is added before neutralization in aqueous form, as demonstrated in Example #4. Esters having the worst odor and yield were obtained when there was no pretreatment with sodium borohydride, the catalyst was not filtered, and hydrogen peroxide was added to the anhydrous crude ester, as demonstrated in Examples #29 and #30 below. See Table III for comparative results.
The catalyst may be selected from the group consisting of stannous oxalate and metal oxides, such as zinc oxide. Stannous Oxalate is a catalyst in the category or group of Organometallics. It is also referred to as an organotin catalyst. Stannous Oxalate may be used in the range of 0.05% to 1.5% on the weight of the alcohols. Metal oxides in general, and zinc oxide in particular, may be used as catalysts in the range of 0.1% to 1.0% on the weight of the alcohols.
The preferred catalyst is Stannous Oxalate, which is insoluble in the reaction mixture, in the alcohol alone, or in the carboxylic acid alone. The advantage of using this catalyst is that it can be filtered or removed by other means from the crude ester. Methane sulfonic acid is not used as a catalyst because it cannot be physically removed by filtration or otherwise easily removed from the crude ester, unless it is washed.
The catalyst is removed from the crude ester after the reaction is complete and before neutralization. The reaction is deemed complete when the acid value is less than 10 mg KOH/g.
The reaction mixture may optionally be cooled to room temperature before removing the catalyst, preferably by filtration. Filtration may be accomplished by any conventional means, including using cartridges, filter strainers, filter press, or centrifuge. Thus, the products containing stannous oxalate and zinc oxide as catalysts are filtered to remove the heterogenous catalyst.
The next step is neutralization/washing of the optionally cooled crude ester which has been filtered. The crude ester with its acidity of no more than 10 mg KOH/g is neutral washed with stoichiometric, or slightly greater than stoichiometric, amounts of alkalis. This guarantees that acidity of the crude ester is overcome. This can optionally be verified by testing for acid value in the top layer of the mix. An acid value of 0 indicates that acidity has been completely neutralized. The alkalis can be sodium or potassium salts such as carbonates or hydroxides. The quantity of wash water can be from 1% to 25% on the weight of crude filtered ester. Sulfate salts or chloride salts of sodium or potassium are used at levels of 1% to 25% on the weight of total waters used for neutralization and/or washing. Thus, the optionally cooled but filtered crude ester is washed with neutralizing solutions containing an alkali metal carbonate to neutralize acidity of the catalyst and reactants, and sodium chloride or sodium sulfate. The sodium chloride or sodium sulfate salts are added for the purpose of phase separation of the two-phase systems of neutralizing/washing mixtures, i.e., the aqueous and organic phases. Phase separation is done at a temperature of 20xc2x0 C. to 100xc2x0 C., preferably between 40xc2x0 C.-100xc2x0 C., and more preferably between 60xc2x0 C.-100xc2x0 C.
After neutralization is complete, as evidenced by zero acidity and minor alkalinity, which assures acidity has been neutralized, then a certain quantity of hydrogen peroxide is added to the same first wash containing crude ester, water, sodium carbonate, and sodium sulfate, for the purpose of treating the ester, and especially for the purpose of bleaching the ester. If hydrogen peroxide is added before neutralization is complete, an odorous ester will result. The degree of odor depends on the stage of completion of neutralization. The more complete the neutralization of acidity, the better the odor of the resultant ester.
The concentration of hydrogen peroxide in its 30%-35% commercially available strength is in the range of 0.02% to 2.0% on the weight of the crude ester. This translates to a range of 6 ppm to 7000 ppm levels of hydrogen peroxide. Hydrogen peroxide is added to bleach the slight darkening in the reaction mixture.
The crude ester is in contact with hydrogen peroxide only in its abundantly wet form, i.e., only in the presence of large quantities of wash water or neutralization wash waters. Thus, if it is desired to bleach the reaction mixture with hydrogen peroxide, the treatment with hydrogen peroxide is done during the alkaline wash, but after the alkalines are entered and have neutralized the acidity, rather than in the anhydrous form of the crude ester. The use of hydrogen peroxide on the anhydrous crude ester at elevated temperature is believed to give or impart an odor to the composition which does not diminish subsequently, during the washing processes, as demonstrated by Ex. #29 below.
If the hydrogen peroxide is added simultaneously, i.e., in one step, with the neutralization or wash waters, as taught in the ""097 and ""461 Patents to Walele et al., supra, there is no improvement in the odor or color of the resultant ester. However, applicants have discovered that if the catalyst is removed, and hydrogen peroxide is added sequentially to the neutralization or wash waters, after neutralization is complete, esters having improved odor, color and yield are obtained.
In other words, it is not required in the invention process to add hydrogen peroxide. However, it is sometimes desirable to add hydrogen peroxide to improve (whiten) the color of the resulting ester. If it is desired to add hydrogen peroxide, it must be added after neutralization is complete, during the washing step, or after the washing step, while the ester is still wet, to eliminate or significantly reduce the odor of the resulting ester.
The process of the invention uses hydrogen peroxide in the aqueous washings (after neutralization is completed) to avoid contacting the anhydrous crude ester with hydrogen peroxide. Preventing hydrogen peroxide from contacting the anhydrous crude ester avoids the oxidation, if any, of the organic unreacted matter of the reaction mass. This prevents imparting an odor to the ester which cannot be washed out later.
Applicants have found that when hydrogen peroxide is added after neutralization of the acidity, the odor of the resulting ester is much improved, especially when the catalyst is removed. Applicants theorize this is because the chances of other side reactions occurring are negligible. For instance, the oxidation of alcohol to aldehydes, which typically creates odorous compounds, does not occur. This was not the case with prior art processes, such as that taught by U.S. Pat. No. 4,791,097 to Walele et al. In the ""097 Patent, water, salt, sodium carbonate and hydrogen peroxide were added together simultaneously, without filtration of the catalyst, before neutralization of the acidity. The resultant ester has a strong odor, dark color, and poor yield, as shown in Example #31, below.
Applicants have found that odorous esters are formed when the anhydrous crude ester comes into contact with hydrogen peroxide at high temperatures of 80xc2x0 C. to 100xc2x0 C. in the presence of a catalyst, such as stannous oxalate.
It is preferred to have a second wash to remove alkalinity. The alkalinity is-removed easily by washing with water containing a salt, such as sodium sulfate or sodium chloride. The wet ester so obtained may also be subjected to a third wash of water and salt to insure no alkalinity remains. Then the wash water is removed.
The wet ester is contacted with hydrogen peroxide after neutralization is completed, in the same wash bath with the products of neutralization. Alternatively, hydrogen peroxide may be added separately, in a subsequent wash, after removal of the first wash water, following phase separation, while the ester is still wet and after neutralization is complete.
The next step is drying of the esters. The washed ester is subjected to drying at 100xc2x0 C.-120xc2x0 C. under reduced pressure of up to 1-5 mm Hg and until the residual moisture is less than 0.05%.
A final filtration step follows. The dry ester is filtered using diatomaceous earth filter aids.
Thus, applicants have found that removal of the catalyst before neutralization washing of the acidity with alkali, followed by drying of the ester, will result in odorless ester with some color. For exceptional color, hydrogen peroxide may be added to the filtered crude ester after neutralization of acidity and before drying in low pressure. There should not be any free hydrogen peroxide in the system. This will make possible the production of very low odor to odorless esters with good color.
Where the catalyst is not removed and hydrogen peroxide is added, the resultant ester has good color, but is odorous. Simply removing the catalyst and not adding hydrogen peroxide results in esters which are odorless and have some color. Removing the catalyst and adding hydrogen peroxide results in esters which are odorless and have good color, i.e., very low color.
Thus, the advantages provided by this invention are primarily production of an odorless ester, and improvement in the color and yield of the ester.
The benzoate esters of this invention may be used in skin care and personal care compositions. The amount used in skin care compositions is dependent on the type of skin care composition, the type and quantity of other ingredients, such as cosmetic ingredients used, and the amount and type of functional additives that are utilized. Typically, the amount of benzoate ester used ranges from about 0.5% to about 80%, by weight, of the skin care compositions. For example, a facial cream may only have about 0.5%, while a massage oil may have up to about 80% by weight.
Still higher amounts may be used in, for example, bath oils, e.g. 95%.
Further, the benzoate esters of this invention possess other unusual physio-chemical properties, which can make them suitable for use as emollient carriers in cosmetic formulations, and for use as solvents and emollient carriers in general cleaning compositions, such as in hand, face, and body creams and lotions. Thus, the benzoate esters described herein may serve not only as emollients and carriers, but may also exhibit one or more other functions.
The benzoic acid esters and emollient esters of the invention have properties in common with the C12-C15 benzoate and other esters of the prior art, such as the ""545 Patent to Scala, in terms of being less greasy, less oily having low cloud point and pour points, low toxicity, ease of emulsification, high spreading coefficient, acid and alkaline stability, the ability to form gels with suspending agents, water solubility/dispersibility, and the ability to act as solvents for many common skin and hair care ingredients. This is because the process of the invention utilizes the same starting or raw materials as the ""545 Patent to Scala, but uses a different process to produce the esters. The process of the invention results in the production of esters having improved odor and color, and greater yields, as compared to the esters of the ""545 Patent to Scala. The improved yield is a further benefit of the process of the invention; by removing the catalyst there are less impurities to be washed, and no side reactions occurring during washing.
The following are non-limiting examples of processes for preparing the ester compositions of the invention and comparative examples of processes for preparing ester compositions of the prior art (Examples 1 to 31); uses of the compositions in specific cosmetic or personal care product formulations wherein the property of reduced or no fragrance is useful (Examples 32 to 35); and odor panel test results (Examples 36 to 37). In the Examples, as well as throughout this application, the chemical and scientific symbols have their customary meanings and all percents are weight percents unless otherwise specified.
Example Nos. 1 through 31 identify esters produced by the old process, and the new process of the invention. For ease of identification, each ester is identified by both an Example Number and a Reference No., where applicable. This identification system is used in the subsequent Tables III, III-A, III-B, III-C and III-D.
By xe2x80x9cother processxe2x80x9d in the Examples below, and the corresponding Tables, unless otherwise specified, is meant a process of the prior art as described, using FINESOLV TN(copyright) available from Finetex, Inc. as the raw material, wherein the catalyst is not removed during the reaction before neutralization and washing. Unless otherwise specified, it is not intended to refer to the exact process taught in the ""545 Scala patent, as Scala teaches use of MSA as a catalyst, and the invention contemplates use of stannous oxalate or zinc oxide as the catalyst. Furthermore, Scala teaches reacting MSA at a lower temperature than the stannous oxalate catalyst is reacted at in the process of the invention. Color in the Examples below is measured using ASTM D-1209 on the APHA scale of the American Public Health Association. APHA scores less than 20 denote good color, with scores of 5 to 10 signifying superior color, i.e., clear color or absence of color. APHA scores over 20 are not good, as a yellow tint is visible, becoming progressively more colored as the APHA scores increase.